Another three people died in two separate strikes shortly afterwards, one hitting Shejaiya in eastern Gaza City and a second in Jabaliya in the north.

Two Palestinian youngsters look through the rubble of their destroyed house after an Israeli air strike in Beit Lahiya in the northern Gaza strip (EPA)

The Israeli army confirmed it had struck "a few targets in northern Gaza City."

The latest deaths hiked the Palestinian death toll to 64 in almost 100 hours of raids, while three Israelis have been killed by rocket fire since Wednesday.

Israeli aircraft also hit two media centres in Gaza City on Sunday, wounding at least eight journalists, one of whom lost a leg, health ministry spokesman Ashraf al-Qudra told AFP.

The military defended the strike, saying it had targeted Hamas operational communications and sought to minimise civilian casualties.

Israeli soldiers sit atop their tanks on the Israeli side of the border with the Gaza Strip (AFP/Getty Images)

Barack Obama said on Sunday it was "preferable" for the Gaza crisis to end without a "ramping up" of Israeli military activity.

"Israel has every right to expect that it does not have missiles fired into its territory," Obama said in Thailand. "If that can be accomplished without a ramping up of military activity in Gaza, that is preferable."

In Cairo, senior Hamas officials said Egyptian-mediated talks with Israel to end the conflict were "positive" but now focused on the possible stumbling block of guaranteeing the terms of a truce.

An outcome acceptable to Hamas would be assurances by the United States, Israel's main backer, to be the "guaranteeing party," one official said on condition of anonymity.

Security officials in Cairo said an Israeli envoy also arrived in Cairo on Sunday for Egyptian-mediated truce talks with Hamas.

Israel's Foreign Minister Avigdor Lieberman, meanwhile, insisted that "the first and absolute condition for a truce is stopping all fire from Gaza," and that all armed groups would have to commit to it.

Earlier, Prime Minister Benjamin Netanyahu warned that Israel was ready to "significantly expand" its operation against Gaza militants even as he prepared to receive French Foreign Minister Laurent Fabius, who is on a whirlwind truce mission to the region.

"We are extracting a heavy price from Hamas and the terror organisations," Netanyahu said at the weekly cabinet meeting. "The army is prepared to significantly expand the operation."

Mr Netanyahu said he was holding ongoing talks with world leaders, "and we appreciate their understanding of Israel's right to self-defence," as thousands of Israeli troops massed along the Gaza border.

But William Hague, the foreign secretary, pressed Israel not to escalate the conflict by sending ground troops into the Hamas-run Palestinian territory.

"The prime minister (David Cameron) and I have both stressed to our Israeli counterparts that a ground invasion of Gaza would lose Israel a lot of the international support and sympathy that they have in this situation," he said.

Since the start of its Operation Pillar of Defence, launched after the killing of top Hamas military Commander Ahmed Jaabari in an air strike, the Israeli army says Palestinian militants have fired more than 800 rockets over the border.